lang/langfilter/Lang.hs

module Lang where

import Text.Pandoc.Definition
import Data.Char (toLower)
import qualified Data.Text as Text
import System.IO
import Data.Text (Text)

data Lang = Lántas deriving (Eq, Show)

type Vars = (?lang :: Maybe Lang, ?defColor :: Text)

toText :: Maybe MetaValue -> IO (Maybe Text)
toText (Just (MetaInlines [Str s])) = toText (Just (MetaString s)) -- ugh
toText (Just (MetaString s)) = pure $ Just s
toText Nothing = pure Nothing
toText (Just ℓ) = do
  hPutStrLn stderr $ "[WARN] expected a string, got: " <> show ℓ
  pure Nothing

toLang :: Maybe MetaValue -> IO (Maybe Lang)
toLang m = do
  mres <- fmap (Text.map toLower) <$> toText m
  case mres of
    Just res -> do
      if res `elem` ["laantas", "lántas"] then
        pure $ Just Lántas
      else do
        hPutStrLn stderr $ "[WARN] unknown language: " <> show res
        pure Nothing
    Nothing -> pure Nothing